Khedia Jackson, Agarwal Parinita, Agarwal Pradeep K
Academy of Scientific and Innovative Research, CSIR-Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, Bhavnagar, India.
Division of Biotechnology and Phycology, CSIR-Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, Bhavnagar, India.
Front Plant Sci. 2018 Oct 29;9:1522. doi: 10.3389/fpls.2018.01522. eCollection 2018.
NAC proteins are a large family of plant-specific transcription factors which regulate both ABA-dependent and -independent gene expression. These transcription factors participate in biotic and abiotic stress-response through intricate regulation at transcriptional, post-transcriptional and post-translational levels. In the present study, AlNAC4 transcription factor was isolated from a salt excreting halophyte . The has an open reading frame of 936 bp, encoding a protein of 312 amino acid, with an estimated molecular mass of 34.9 kDa. The showed close homology to monocot NACs in the phylogenetic tree. analysis revealed that AlNAC4 possess the characteristic A-E subdomains within the NAC domain. The AlNAC4 showed sixteen post-translational phosphorylation sites. The transcript was significantly upregulated with dehydration and HO treatments, showing its role in osmotic and oxidative stress, respectively. The recombinant protein showed binding to mono as well as tandem repeats of NAC recognition sequence (NACRS) of the promoter. This is the first report mentioning that overexpression of improved oxidative stress tolerance in tobacco transgenics. The transgenics maintained ROS homeostasis during HO treatment. The transgenics showed regulation of stress-responsive genes including , , , , and transcription factors like , during oxidative stress. The AlNAC4 transcription factor from recretohalophyte Aeluropus showed regulation with abiotic stresses and binding to NACRS elements of promoter. The tobacco transgenics showed improved growth with oxidative stress.
NAC蛋白是植物特有的一大类转录因子，可调节依赖脱落酸和不依赖脱落酸的基因表达。这些转录因子通过在转录、转录后和翻译后水平上的复杂调控参与生物和非生物胁迫反应。在本研究中，从一种泌盐盐生植物中分离出AlNAC4转录因子。其开放阅读框为936 bp，编码一个312个氨基酸的蛋白质，估计分子量为34.9 kDa。在系统发育树中，该蛋白与单子叶植物NAC蛋白具有密切的同源性。分析表明，AlNAC4在NAC结构域内具有特征性的A-E亚结构域。AlNAC4有16个翻译后磷酸化位点。该转录本在脱水和过氧化氢处理下显著上调，分别显示出其在渗透胁迫和氧化胁迫中的作用。重组蛋白显示与启动子的NAC识别序列（NACRS）的单重复和串联重复序列结合。这是首次报道AlNAC4过表达提高了烟草转基因植株的氧化胁迫耐受性。转基因植株在过氧化氢处理期间维持活性氧稳态。转基因植株在氧化胁迫期间显示出对应激反应基因（包括、、、、）以及转录因子（如、）的调控。来自泌盐盐生植物獐茅的AlNAC4转录因子显示出对非生物胁迫的调控以及与启动子的NACRS元件的结合。AlNAC4烟草转基因植株在氧化胁迫下生长得到改善。
